Endotracheal tubes have long been accepted to establish a direct path from the trachea to the ambient exterior or to a ventilation machine. However, endotracheal intubation requires a high degree of skill and the use of supporting medical devices such as a laryngoscope for visualization of the glottis. Furthermore, an endotracheal tube on its way to a trachea passes into the larynx and adjacent to delicate structures which poses a potential for serious damage to this important speech organ. Accidental insertion into the esophagus can also occur.
Supraglottic masks which do not intrude into the trachea avoid the known problems of endotracheal tubes. Laryngeal masks, as a supraglottic device, have become accepted alternatives to avoid the need of sealing within the trachea or the accidental insertion of the endotracheal tube into the esophagus.
Early versions of alternatives to endotracheal tubes used inflatable cuffs but needed an exterior face mask placed over the face of the patient to stop air leakage while the patient is being ventilated via the air ports.
One widely accepted laryngeal mask device is disclosed in U.S. Pat. No. 4,509,514 to Archibald Brain. This artificial airway device is in the form of a laryngeal mask airway. This laryngeal mask airway comprises of a tube opening into the interior of a mask portion. The periphery of the mask may be inflatable and provides a seal around the inlet of the larynx.
A disadvantage related with the use of this traditional laryngeal mask device is encountered in patients who are at risk from vomiting or regurgitating stomach contents while unconscious. Although the device is known to form a seal around the laryngeal inlet sufficient to permit artificial ventilation of the lungs, this seal may be sometimes insufficient to prevent lung contamination during retching, vomiting or regurgitation. Besides, the bulk size of these devices may impede, or create difficulties to the prompt access to the esophagus for the passage of an oral or nasal gastric tube to drain eventual esophageal/stomach contents. Due also to its design, it is possible that when a certain ventilation pressure is reached or when the device is not properly placed, a leak of gases from the repetitive ventilation attempts may reach and enter the esophagus, inflating the stomach increasing the risk of regurgitation and discharge of its contents.
In order to minimize these serious problems, modifications were proposed and introduced on these laryngeal mask ventilation devices to provide a sort of gastric drainage as disclosed in U.S. Pat. Nos. 5,241,956 and 6,439,232 to Brain. These were all basically designed by adding a second esophageal tube, ending at the supraglottic mask distal cuff tip. This second tube is usually molded by a semi rigid open ring, inside the body of the pneumatic cuff of the mask. This construction, when all is working well, allows the hollow orifice of the esophageal tube to be properly aligned with the esophageal entrance, so it could drain its content or allow a passage of an oro-gastric tube through it.
However for this device to work, proper insertion and positioning of the ventilation device (supraglottic mask) at the hypopharynx is critical. Its tip must be properly facing the esophageal entrance. If the mask is not in the right position, the proposed esophageal draining may not properly occur which may result in an increased risk of leakage of the esophageal/gastric contents. Any such contents may then be undesirably aspirated into the lungs with serious consequences. In order to accommodate an esophageal draining tube in addition to the tracheal tube, the thickness of this device is increased. The increased thickness may make proper insertion and installation of the device into the patient's throat more difficult.
Another device directed to reducing the risk of regurgitation and at the same time to provide for lung ventilation is disclosed in U.S. Pat. No. 5,499,625 by Frass. This is a twin lumen coaxial device designed for use in emergency situations and difficult airways. It can be inserted blindly into the oropharynx and usually enters the esophagus in about 90% of times. It has a low volume inflatable distal cuff and a much larger proximal pharyngeal cuff designed to completely occlude the oropharynx and the nasopharynx. It provides effective lung ventilation regardless of whether esophageal or tracheal placement is accomplished. When it is placed in the trachea, it functions as an endotracheal tube, with the distal cuff sealing the tube against the tracheal wall. When its distal cuff is in the esophagus, ventilation is possible through a second lumen that ends at perforations at the pharyngeal side of the tube above the lower cuff that occludes the esophagus and below the upper pharyngeal cuff. Due to its design, this device is limited to unconscious patients over five feet (5) in height. Furthermore, an operator needs to be aware of symptoms to assure proper placement. If auscultation of breath sounds are negative and gastric insufflation is positive, the operator needs to immediately switch the lumen to provide air into the alternate airway. Its positioning is critical, as the airway could be occluded if not properly placed and the proper lumen is not used.
U.S. Pat. No. 4,995,388 to Archibald I. Brain discloses a larynx mask with a drain tube intruding into the esophagus and with an esophageal sealing cuff. Proper insertion of this particular device is very difficult. Also, in this device, the inflation line leads to the pharynx cuff and then serially down to the esophageal cuff.
U.S. Pat. Nos. 5,241,956; 5,355,879; 5,632,271; and 5,878,745 to Archibald Brain disclose a respective larynx mask with two inflatable seals for sealing about the pharynx. The seals may be inflated by a common inflation line or by separate inflation lines.
U.S. Pat. No. 4,016,885 to Bruner issued on Apr. 12, 1997, has described a device to indicate the gas pressure in inflatable cuff-type catheters, by expansion of the cuff and scaling this expansion. The main goal of Bruner's device is to provide a pressure indicator for endotracheal and tracheostomy tubes, to avoid trauma due to overpressure. This is mainly achieved by employing an open ended spring wound at the mid-section of an elliptically shaped expansion chamber. However, this device is not designed to measure and alert the occurrence of under pressure events.
What is needed is a supraglottic mask with an esophageal drain tube and esophageal cuff in combination with an improved seal on the pharynx cuff, an improved pressure indicator, and an improved method of installation that will quickly form an esophageal obturator to reduce risk of choking on gastrointestinal contents.